Gentlemen
I have decided to 'bite the bullet' in many ways it seems, the wife bought me a milling machine some time ago, it is time to re-animate it, [just waiting for a good thunderstorm didnt work], it is a cincinatti toolmaster of French parantage, have removed the spindle etc, gearbox for the head vertical feed has been removed, it has sustained some damage, a bent shaft and a worm/wheel arrangement that looks like it partially done its sacrificial job as it is ali, the teeth are showing signs of plastic deformation/shearing, hard to tell exactly as i didnt have te right glasses on but will later.
It is a small 3"x 3/8" gear that engages a worm.
Its apparent that it needs to be replaced.
The question; i have available a horizontal miller, a small dividing head, a lathe and drill.
Should i a, use mill and dividing head or b, make some kind of hob like the worm with teeth [lol] and use the lathe?
i'll add some photos after when i get my camera back, as well as some of the dimantling and bearing change.
Alternativly i could just buy one stock i suppose, either way gearcutting sounds much more fun and truthfully i have never even used the dividing head yet and the sin is i have 2 that were donated by my local scrap skip, along with the mill itself.
your thoughts are appreciated as i'm unsure of where to go next
thanks
mark

Ian B

06-19-2012, 10:15 AM

Mark,

As the aluminium one has already failed, this might be an opportunity to use a stronger material - brass, or better, bronze.

If I were doing it, I'd machine the wheel to size, and machine a hollow ring around the periphery, to match the core diameter of the worm. Then, hold the wheel in a dividing head and very roughly gash out the right number of teeth.

Machine up a piece of hardenable steel to match the worm. Mill or grind teeth along its length and harden it. If you make the flutes reasonably wide, you can probably get away without relieving the teeth.

Mount the 'hob' in the lathe chuck, mount the wheel on a vertical spindle with a thrust bearing beneath it. Line the gashes up with the teeth on the hob, start the lathe, feed it in.